The present disclosure relates to measuring the pressure of a fluid flowing through a fluid line and, in particular, to the use of a piezometer ring to measure the average pressure of the fluid.
Piezometer rings are used along with pressure sensing devices to measure the average static pressure of a gas flowing through a fluid line. The piezometer ring is coaxial with and along the fluid line. To get a measurement of the average pressure, the piezometer ring includes a number of holes that are equally spaced circumferentially around the piezometer ring. The holes extend from the main fluid channel that flows through the ring to a groove on a radially outer side of the piezometer ring. Within the groove, the pressures at each of the holes in the piezometer ring are combined to form an average pressure of the gas within the fluid line (i.e., with the channel through the piezometer ring and fluid line). To measure that average pressure, a pressure sensing device is fluidically connected to the groove in the piezometer ring by a sense line connected to a sense hole adjacent the groove. Due to space constraints around the piezometer ring and fluid line, the sense line and sense hole may be in a bottom of the piezometer ring. With the sense line and sense hole in the bottom of the piezometer ring, the sense line and sense hole are susceptible to being filled with liquid that may undesirably accumulate within the fluid line and that can flow through the holes in the piezometer ring, into the groove, and then into the sense line. If the sense line is filled partially or entirely with fluid, the pressure sensing device may not be able to accurately measure the pressure within the fluid line.